This is an anti-quackery and pro-neurodiversity blog. Most posts here have to do with the author's view that autism is not a new man-made phenomenon, but instead a natural part of our species that has always been with us, and should continue to be. Reasonable corrections and rebuttals are welcome and encouraged.

Saturday, August 12, 2006

No Autism Epidemic: An Update

This is a revision of a post I wrote about 5 months back. I will include many new arguments and data I've come across since then. As usual, those who believe that an autism epidemic has definitely occurred are invited and encouraged to debate the evidence presented.

Changing characteristics

Dr. Eric Fombonne has said that comparing current autism prevalence to a prevalence from studies 30 years ago is like comparing oranges to sheep. Another way to express this is that the diagnoses are not equivalent. But even with (presumably) the same subjective diagnostic criteria it is possible for diagnosed groups of autistics to be inequivalent as time goes by. This hypothesis (let's call it the expanding criteria hypothesis) is verified by looking at client characteristics in the California DDS data. See Table 1.

Table 1: Changes in autistic client characteristics over time

Quarter

Epilepsy

Profound MR

Severe Behaviors

Lack of MR

Q2 1992

15.6%

11.2%

22.9%

27.8%

Q4 1996

11.8%

7.4%

20.5%

41.2%

Q4 2000

8.7%

4.4%

19.2%

52.4%

Q4 2004

7.1%

2.6%

17.4%

61.9%

Q4 2005

6.7%

2.4%

16.8%

63.6%

Every quarter, as caseload rises above what would be expected from changes in the population of the state of California, the proportion of certain characteristics of CDDS autistic clients simultaneously drop. As a group, autistics in California today are quite inequivalent to autistics in California in 1992. Effectively, autism one quarter in California is not equivalent to autism the next quarter. Therefore, it is not possible to say that a real increase in autism prevalence has occurred.

The following figure [courtesy of CDDS] also illustrates the point. Notice that the autism curve and the autism without MR curve run almost parallel to one another.

Evidence from regional differences

The bulk of the "epidemic" in the state of California occurred in the Los Angeles area, as illustrated by the following figure [courtesy of CDDS]:

Current differences in administrative prevalence between regional centers are substantial. Table 2 shows caseloads of various CDDS categories in the Westside RC and the Central Valley RC, expressed as ratios to the epilepsy caseload.

Table 2: Q4 2005 comparison of Westside and Central Valley

Regional Center

Autism Ratio

PMR+SMR Ratio

PMR Ratio

Epilepsy Ratio

Severe Behavior Ratio

Central Valley

0.32

0.60

0.36

1.0

0.31

Westside

1.61

0.68

0.31

1.0

0.45

It is telling that despite the 500% difference in administrative prevalence of autism between Westside and Central Valley, there is apparently no difference in the prevalence of mental retardation between these two regional centers. If regional prevalence differences are not real, we can extrapolate and conclude that state-wide prevalence changes over time could also not be real.

The hypothesis that regional prevalence differences may be due to environmental factors, such as pollution, appears to be improbable, as I recently argued.

Caseload growth patterns are telling in that regard. Note that the highest annual caseload growth (in percentage terms) in California occurred in the 2002-2003 timeframe. It was about 20%. Currently, the Central Valley regional center, which has the lowest prevalence of autism in the state, has an annual caseload growth of 24%. Autism in Central Valley is currently undergoing what might be described as staggering growth. In contrast, the Westside regional center, with the highest prevalence in the state, has an annual caseload growth of just over 8%. It is not far fetched to suppose that, eventually, Central Valley will catch up to Westside, and that it was simply behind in its recognition of autism.

Evidence of diagnostic substitution

Shattuck (2006) found that as the prevalence of autism has risen in the United States, the prevalence of idiopathic mental retardation and learning disability has undergone a corresponding decline.

California was one of a handful of states that does not clearly follow this pattern, according to Shattuck. But as noted, expanding criteria is what apparently drives most of the autism caseload growth in California. We also know that the recognition of autism in the population with mental retardation in California was around 3.5% in 1992, whereas it is about 7% today. This recognition varies considerably from one regional center to the next. Typically, but not always, regional centers with lower autism prevalence have a lower proportion of clients with autism in the mental retardation category. Note that de Bildt et al (2005) states that the most reliable and well-founded estimate for the prevalence of PDD in children and adolescents with mental retardation is the DSM-IV-TR prevalence of 16.7%. So the California recognition of autism in this population still has considerable room for additional growth, and it is not far fetched to conclude that improving recognition (i.e. diagnostic substitution) has occurred in California over time, even though this is not the most significant factor driving caseload growth in that state.

High prevalence in adults

Stahlberg et al (2004) found that 30% of consecutively referred adult patients with ADHD had "comorbid" ASD. If we consider that the prevalence of ADHD in adults is estimated at about 4.2% as of 2006, it would appear that the prevalence of ASD in adults can be at least 126 in 10,000. Granted, Stahlberg's ADHD patients could be more "severe" than usual, but his findings are notable considering the limited screening of a specific population.

Nylander & Gillberg (2001) found that 89.5% of adult psychiatric outpatients with "definite ASD" had previously been missed. They had received other psychiatric diagnoses, such as schizophrenia.

Baron-Cohen et al (2001) found that 2% of randomly selected adult controls scored 32 or higher in the AQ test. Further, 7 of 11 interviewed students who were high-scorers met threshold criteria for a DSM-IV diagnosis. It would appear then that the prevalence of ASD in adults can be as high as 127 in 10,000 if screened thoroughly. This does not even consider those autistics who are missed by an AQ score threshold of 32.

Mark Blaxill's "hidden horde" appears to not be hiding very well, because it has been found repeatedly.

Evidence from prevalence studies

When we compare apples with apples, the huge increases of autism prevalence often claimed to have occurred seem to vanish. Williams et al. (2005) provides a systematic review of prevalence studies. The researchers conclude that 61% of the variation among prevalence studies may be explained by a model that includes diagnostic criteria used, age of children screened, and study location. Note that this model does not even consider awareness or cultural factors.

What went on in the past

One of us (LW) was involved in the planning of the study by Vic Lotter [1966] of 78,000 children aged 8, 9, and 10 years living in the former English county of Middlesex. This was the study in which the 4-5 in 10,000 prevalence rate was first found. I (LW) know what sorts of children were included as classically autistic because I was one of the small group (Neil O'Connor, John Wing, Vic Lotter and myself) who decided on the criteria. In those days we were interested only in really classic Kanner's syndrome and Vic was determined to keep the criteria as narrow as possible. Later, in the Camberwell study described above, Vic was shown case histories of the children Judy Gould and I thought fitted Kanner's descriptions - to our surprise, Vic said we ought to exclude some because they were not classic enough! I think it is fair to say that, when Vic specified narrow criteria, they were NARROW.

When Judy Gould and I started the Camberwell study, we still thought that Kanner's autism could easily be differentiated from other developmental disorders.. By the end of the study our ideas had been turned upside down. We had learnt from direct experience that the psychological dysfunctions underlying autism were manifested in many different ways, far beyond the boundaries of Kanner's syndrome. We developed the hypothesis of an autistic spectrum based on the triad of impairments of social interaction, communication and imagination. Because we concentrated on the children with learning disabilities (IQ under 70) we saw very few with the pattern described by Asperger. We had to wait for the study by Christopher Gillberg in Gothenberg to find out how many children with IQ of 70 and above were also in the autistic spectrum. As described above, combining the results of these two studies gave an overall prevalence rate for the whole autistic spectrum, including those with the most subtle manifestations, of 91 per 10,000 - nearly 1% of the general population.

The epilepsy argument

Autism has been linked to a seizure liability, and the CDDS data itself shows that the prevalence of epilepsy among autistics is considerably higher to that of the general population. It follows that an environmental trigger capable of producing an epidemic of autism might also result in an epidemic of epilepsy. Surprisingly, we find in the data that the epilepsy caseload grows at about the same pace as the population in the state of California. Additionally, the prevalence of epilepsy does not appear to depend on degree of urbanization.

The mental retardation argument

An epidemic-causing environmental trigger that results in brain injury should be expected to increase the probability that an individual will have mental retardation, and thus result in an epidemic of all levels of mental retardation. But again, there is no evidence of an increase in the prevalence of mental retardation. In California, the mental retardation caseload increases at about the rate that should be expected from population growth.

Furthermore, it is known that the average IQ score has actually risen over time and IQ tests have to be re-normalized periodically (see Flyyn effect). While this does not necessarily say anything about autism, it should at least put to rest fears that an epidemic of neurological disorders will "destroy the United States."

The institutionalization argument

Proponents of an autism epidemic generally not only refer to autism, but to an increase in the prevalence of all sorts of neurological disorders. They also often refer to the increased fiscal burden that will presumably result from this epidemic. While increased awareness can result in increased service expenses, I contend that there are certain types of services that are not likely to be significantly affected by increased awareness. Let's look at institutionalization of developmentally disabled individuals in the state of California.

In Q2 1992, the total number of institutionalized individuals registered with CDDS was 32,943. In Q2 2005, the number was 36,869. Adjusting for population growth, we get 10.6 per 10,000 persons institutionalized in 1992 vs. 9.97 per 10,000 in 2005. There appears to be a decrease in the prevalence of institutionalized individuals with developmental disabilities, which is a positive trend.

Granted, very young children would not tend to be institutionalized, but even in the younger age cohorts the CDDS data shows a decreasing trend in number of institutionalized clients. At the very least, this should lay to rest fears that a generation from now institutions will be overflowing with adult autistics.

The speech delay argument

Speech delay is perhaps the most characteristic feature of autism. If there has truly been an epidemic of autism resulting from an environmental trigger which is not necessarily autism specific, one might expect to find an increase in the prevalence of speech delay. There is no evidence of such an increase. Epidemiological data is hard to compare due to differences in methodology and criteria, but let's look at some studies over time. Stevenson & Richman (1976) found a prevalence of 3.1% for delayed language development and 5-7% for specific language delay. Silva et al (1987) reported a prevalence of 4.6% for expressive language delay. Wong et al (1992) found a prevalence of 6.1% for expressive language delay. Shriberg et al (1999) found that he prevalence of speech delay in 6-year-old children was 3.8%. There are no indications of an increase in the prevalence of speech delay concurrent with the "autism epidemic".

Refutation of a common argument

A study by the MIND Institute (2002) determined that there was "no evidence that a loosening in the diagnostic criteria has contributed to the increased number of autism clients served by the Regional Centers." These findings have often been cited in favor of the epidemic argument. The study assesed an earlier cohort and a more recent cohort of clients using the DSM-IV criteria. Since both cohorts met the criteria at the same rate, the researchers concluded that a losening of the criteria cannot account for an increase in autism prevalence. Gernsbacher et al document the obvious reasoning flaw, using a height analogy. Briefly, while both cohorts meet DSM-IV criteria, they are not necessarily equivalent. It is possible the earlier cohort meets a more restrictive criteria than DSM-IV which the more recent cohort might not.

Conclusion

The state of the evidence is not simply sufficient to allow suspending the belief that an epidemic of autism has occurred. It is my opinion that there is enough evidence to assert that said epidemic did not occur.

24 comments:

Thank you Joseph for dealing with the California data so succinctly. And the quote from Wing was a delight to read. I remember Dr Ekkehart Staufenberg saying once that every time we have a good idea about autism we usuually find that Lorna had it first.

Dr Staufenberg may also be able to help with some of the hidden horde. He is a forensic neuro psychiatrist and "the Asperger representative on a Royal College of Psychiatrists working party which is about to complete a report which concludes that a large proportion of high-functioning individuals with autism and their carers only ‘surface’ when they come into real or perceived conflict with the criminal justice system or are at risk of coming into conflict with it.

He says such individuals are likely to come from the ‘active but odd’ group of individuals with an ASD identified by Lorna Wing in 1979 during her pioneering work with Judith Gould in Camberwell, south London: individuals on the autistic spectrum who could be characterised as having the desire to interact with other people – but get it wrong."Quote fromAutism and the criminal justice system.

You will see the increase in institutionalization starting soon. It will coincide with the introduction of the HepB vaccine. Less MR among autistics just shows that diagnosticians are recognizing that autistic kids are not always retarded. It does not indicate that kids are being diagnosed as autistic instead of MR. There is no way in hell that "train wrecks" could have been missed. They did not exist. Why do you go to so much trouble to deny the obvious? Instead of "spinning" the stat's, you should be out hunting for the 75 year olds. But, you know that would be a waste of time, don't you?

How soon, John? The trends are showing the opposite of what you predict. And MR is not an either-or diagnosis in CDDS. It's an assessment AFAIK. That is, if a kid is determined to have an IQ below 70, the kid is classified as mentally retarded. The prevalence of kids with IQs below 70 has not increased in any noticeable manner. Interesting, ha? And please stop referring to autistics as "train wrecks". No one is saying that obviously disabled children were not noticed, but they were simply less likely to be labeled autistic. This is pretty simple to understand, John. Further, there is no evidence that 76 years olds are any less likely to be diagnosed autistic as, say, 66 year olds. It's a no-brainer to imagine why 75 year olds might not be interested in seeking a diagnosis of autism (yet, a few do, surprisingly). Face it, John. The prevalence of ASD in adults is high, no matter how much you whine.

Joe; As soon as they are too large for their parents to handle. They'll be 18 in 2009. How do you measure an IQ on a kid like mine who can't read, write or talk? By your standards, he should be diagnosed as MR but isn't. As for the old folks, I'm not saying any of them would seek a diagnosis. If they existed, and were "train wrecks" like my son, they would've been noticed and the epidemic would've been recognized decades ago. What makes you think the few you claim sought their own diagnosis aren't in the early stages of Alzheimer's? Sounds like bad diagnosis to me. Thanks for throwing in the whining comment to demonstrate that you must resort to name calling as you have nothing intelligent with which to refute my assertions.

How do you measure an IQ on a kid like mine who can't read, write or talk?

For kids who are trully untestable, there's a category named "Unknown MR". The RCs are not supposed to just classify kids as MR or without MR because they feel like it.

As for the old folks, I'm not saying any of them would seek a diagnosis. If they existed, and were "train wrecks" like my son, they would've been noticed and the epidemic would've been recognized decades ago.

What makes you think that a child like your son would've been diagnosed as autistic had he been born 20 years ago?

Do you have any idea what portion of the population is classified as mentally handicapped, and how easily it would be for old autistic folks to be in that population?

Thanks for throwing in the whining comment to demonstrate that you must resort to name calling as you have nothing intelligent with which to refute my assertions.

You are the one who can't refute a single argument from the post. Your assertions are just that - assertions. There is no basis whatsoever for anything you claim.

Joe; My son would have been diagnosed autistic if he'd been born in 1931. Nobody could miss it. It's not like your Asperger's where you might just seem to be weird. And, of course, there are lots of weirdos who do not have Asperger's but might jump on the diagnosis out of convenience. There are not any old autistic folks. Even a pending psychologist could recognize autism. No parent could possibly miss the symptoms of it. No parent would settle for a doctor telling them the child was a little slow. Autism is a huge difference from MR or schizophrenia and you know it. I met lots of MR kids when I was young and a few schizophrenics but I never met, or even heard of an autistic person until I saw Rain Man. Sorry, but you can't prove your point unless you can find 1 in 166 autistics who are 75 years old. You can't even find 1 in 10,000.

Who diagnosed your son? Was it the first pediatrician who saw him, or did you have to find an specialist? In 1931, who would've been able to diagnose your son as autistic? Was there anyone able to do that?

Why wasn't Temple Grandin diagnosed as autistic (in the 1950s I believe) and instead got diagnosed as brain damaged? How could she have been missed, John?

Does your son meet Kanner's autism criteria?

Kanner and Eisenberg (1956) discussed Kanner's original conception of autism and the five features he considered to be diagnostic. These were, a profound lack of affective contact with other people; an anxiously obsessive desire for the preservation of sameness in the child's routines and environment; a fascination for objects, which are handled with skill in fine motor movements; mutism or a kind of language that does not seem intended for inter-personal communication; good cognitive potential shown in feats of memory or skills on performance tests, especially the Séguin form board. Kanner also emphasized onset from birth or before 30 months.

In the same paper, Kanner and Eisenberg modified the diagnostic criteria by selecting two as essential. These were:

1. a profound lack of affective contact 2. repetitive, ritualistic behaviour, which must be of an elaborate kind.

Sorry, but you can't prove your point unless you can find 1 in 166 autistics who are 75 years old.

That makes no sense. Why? Because that would only be necessary to prove that autism existed before 1931 at 1 in 166. Not many, even in your side of debate, considers the possibility of autism not existing before 1931 to be a serious one. The debate is really about the existence of an "autism epidemic". So by showing that ASD exists in adults of any age in a proportion similar to that of children, the epidemic argument about the 1990s is completely undermined, and any related arguments about autism not existing in the past are consequently undermined as well.

Joe; Yes, he meets all the criteria. If born in 1931, of course he wouldn't have been diagnosed until at least 1943. As for Grandin, since autism is brain damage, they did not err in her diagnosis. You claim no epidemic while I say it started in the late 1980's so there would be some young adults in numbers approaching 1 in 166. You can not find older adults in those numbers. Since the poisoning began in 1931, you will find some autistics up to age 75 but not older. Sure, you have some anecdotal evidence of some people with autistic symptoms born before 1931 but you do not have genetic tests on them to rule out Rett's and fragile X. Those things are not autism. That's why they have their own different names. You don't know when Rett's and fragile X began because genetic testing was not available. Since Kanner, the leading expert at the time had never seen autism before, we'll have to assume that it was a new invention. In 1999 Verstraeten told us all that it was invented by Eli Lilly in 1931. Geier confirmed that in 2003. Every child who has been cured by removing the mercury also confirms it. You and your associates don't accept that anyone has been cured and you clutch at the straw that no cures have been published in scientific journals. I certainly have no desire to publish it if my kid winds up cured. I'll let other parents know and probably try to have an article published in a newspaper to help get that knowledge out.

If born in 1931, of course he wouldn't have been diagnosed until at least 1943.

You don't understand. I don't think he would've been diagnosed at all, unless Kanner was your neighbor. Even by 1950, how many psychiatrists do you think might have been knowledgeable about autism?

Did the first pediatrician to examine your son diagnose his very obvious autism that could never be missed?

As for Grandin, since autism is brain damage, they did not err in her diagnosis.

You claim true autism is always diagnosed as autism and never missed. It was clearly missed, by your own definition, in Temple Grandin's case. You're contradicting yourself. (As a side note, autism is not known to be brain damage).

You claim no epidemic while I say it started in the late 1980's so there would be some young adults in numbers approaching 1 in 166.

That makes no sense because prevalence did not go from 4 in 10,000 to 60 in 10,000 in a single year. It took the entire decade of the 1990s and some more to reach that level gradually. Further, the studies I cited are not necessarily of "young adults". They are simply of adults.

You can not find older adults in those numbers.

I can only cite what is published. If something hasn't been studied, that doesn't mean it doesn't exist. Either way, there aren't reports on failure to find autism either.

Since the poisoning began in 1931, you will find some autistics up to age 75 but not older.

That's pure nonsense backed up by nothing but circular reasoning and speculation on your part.

(The rest is a rehash of ridiculous arguments you've repeated over and over again everywhere).

Joe; Since he can't talk or write, I don't know what he remembers. He would've been diagnosed because I knew something was wrong with him before he turned one. I would've done the same thing in 1950 that I did in 1997, research the subject. If the doc's didn't have the answer, I'd have found it myself just like I did now. re: Grandin, if someone has autism, they earn that label because their brain is not functioning properly. That's commonly known as brain damage. It may not be a polite term but it's accurate. A bunch of people have taught us that that damage is reversible. It took 70 years for Amy Holmes to make that discovery. A few years later, Deth explained why it is reversible. How is it nonsense on my part that you folks can't find any 75 year olds? Your two loudest women refuse to answer me when I ask them that question. I know, taking the fifth is not evidence of guilt, yeah right. Calling my arguments ridiculous would be fine if you had any answers to show that. You can't answer my arguments so you try name calling again. That means I'm winning.

I would've done the same thing in 1950 that I did in 1997, research the subject.

I see. I take it the pediatrician missed the unmissable completely and you had to figure it out yourself. Good thing there's an internet nowadays.

re: Grandin, if someone has autism, they earn that label because their brain is not functioning properly. That's commonly known as brain damage. It may not be a polite term but it's accurate.

It's not about politeness. All 3 sentences above have zero basis in fact.

A bunch of people have taught us that that damage is reversible.

Clearly. But without any evidence to back that up.

How is it nonsense on my part that you folks can't find any 75 year olds?

It is nonsense because that's not a debate that's likely to be worthwhile, and that's why no one is actively looking into that. If people had been looking into that and they didn't find anything, then you could claim that we "can't find" them.

You can't answer my arguments so you try name calling again. That means I'm winning.

Which "argument" am I unable to answer John? You do know what an "argument" is, right? Asking to disprove hypothesis you conjure up is not an argument John. That's really just a game. It would be like someone asking you to disprove that exorcism doesn't cure autism, and then claiming that since you're unable to disprove it, he must be right.

Joe; The pediatrician only saw him to give him shots. And, he was fine for 9 or 10 months. Since I didn't have a computer in 1997, learning about autism was not much different than it would have been in 1950. Cured kids are evidence whether their cure is published in a scientific journal or not. The reason nobody is looking for 75 year old autistics is because those of you who defend the drug companies know you won't find them. All of your arguments are feeble attempts to discredit the mercury hypotheses. Since that hypotheses has already been proven, all you can do is confuse some people who don't already have all the facts. You're perpetuating a lie to the detriment of any child whose parent has not learned the truth. Admitting the truth now would be a lot easier than later. More kids will continue to recover and each one who does just makes you look more foolish. That's the beauty of spouting your BS anonymously. When a majority of the public learns the truth, you can just disappear and noone knows who you really are so you won't have to answer for your child harmimg lies.

That makes no sense. For starters, you had previously said the pediatrician diagnosed your son as being in a vegetative state. I don't know if you were being serious, but it's clear that the pediatrician missed what you claim is unmissable. Second, it is nearly impossible for you to have found any information about your son's condition in 1950. Anybody can imagine why - do I have to explain it?

You have been asked to provide one example of a child cured by chelation therapy. You claim they abound, but have not been able to produce a single account.

See Kev's post on the subject. Given that Kev's blog is the busiest autism site on the internet, you'd think curebies would flock the post to defend themselves. The closest comment posted about a recovery account was Anonimouse's, who says he's probably still autistic anyway, but did not receive any treatment AFAIK.

The reason nobody is looking for 75 year old autistics is because those of you who defend the drug companies know you won't find them. All of your arguments are feeble attempts to discredit the mercury hypotheses.

Joe; Most normal people couldn't be bothered arguing with Kevin. As soon as we make him look foolish, he just deletes our posts and bans us from his blog. Do you actually think I would give the name of any cured child to you and your ilk? You'd be digging through the bowels of the internet to find every thing those parents ever uttered and your witch would write about it to try to discredit them. Does she get paid by Eli Lilly or the CDC?

I have Asperger's Syndrome. I am a psychology major and will be going on to graduate school to do psych research, focusing in part on ASDs.

I plan in future to do a normative study on the rates of Autistic Spectrum Disorders in adults. Despite that that will be difficult since it's so much easier to count kids who are in Special School District or with disabilities offices, I will be able to begin answering the question of whether or not the adult population mimics the numbers of the proposed child population.

I suspect that a majority of the ASD population falls within the high-functioning ranges. In past, these would not have been diagnosed, especially since AS wasn't even a diagnosis in the US until 1994. This new flux of Aspies in part can account for the rise in that 1/166 because the CDC wasn't counting those with just Autistic Disorder, they were counting the entire Spectrum. And since 1994, the Spectrum has considerably widened and loosened.

I suspect, from interacting with a great many HF adults online of ALL age ranges, that the adult population is probably similar to the child population in numbers-- perhaps a little less, taking into account more HFs populating with each other (so often like attracts like) and having ASD children.

It's possible ASDs have increased in the past centuries. But so have human population numbers, and for a HF ASDer to find a marital partner and have more ASD children is not unusual. I know several couples myself, personally, who fit this bill.

Picture this: One adult Aspie meets someone who is, say, a little OCD or has some other form of Anxiety Disorder and a bit of ADD. These two get married. They have kids. Five of them. One of these kids is autistic but will grow up HFA. Another is an obvious Aspie. A third has ADHD and sensory issues and is a bit OCD. The other two have a mild ADD but no more.

Now, from these two parents, one with an ASD, the other with neurologically-related disorders, they came together, procreated, and made TWO more ASDs for this world, one partial ASD-related, and two mild ADDs. From the numbers of one ASD, come many more.

You get enough of these pairings, rates will slowly go up. But in that sense, it's not an epidemic. If you look at these as characteristics or traits, it's just sexual selection-- something which NATURALLY occurs for all sexual creatures.

I'm not saying that accounts for the rise, alone. No. Better diagnosis, better media coverage and public awareness, a whole new category added to the list-- these have the biggest effects.

But in an actual rate of occurrence (not diagnosis), sexual selection might be helping create more ASDers. Silicon Valley is a good example.

Prufrock; You may be partially right. There may be lots of people out there under 75 years old with mild ASD. The common denominator, however, is not genetics but an inability to excrete mercury. I think you should study families who had Alzheimer's in the older generation and see if it correlates with ASD in younger generations. You must be aware that all ASD comes from mercury since chelation cures the condition by removing the mercury.

Fore Sam, You've written that your son was cured after chelation, and now you're saying his behavior is consistent with severe autism. But that's OK, I understand. You're still grieving. You aren't ready to accept. I've been there, too. It's not easy.

We can't force you to accept what cannot be changed anymore than you can force us to believe that the laws of nature were repealed the day Sam was born.

Where does the quote from Lorna Wing come from? Want to use the reference! :-)

My background: Degree in Chemistry (specialised in analytical toxicology of heavy metals). Have a son with Asperger's, Hubby a likely candidate too (an M3/M4 corridor - silicon valley commuter, double first and DPhill from Oxford, 'needs help with shoe laces' - you know the type). I'm now doing PGCert in Asperger's.

For what it's worth - have mixed views on the mercury and MMR issues (2 controversial issues in one statement!) Agree statistics show no link with MMR, but view stats. with scepticism - my son spent 4 days in intensive care following his MMR - never been able to get him included in any statistics. He 'recovered' naturally and was sent home, being told it was probably a nasty virus. Mercury - hmmm, just know a PhD biochemist mum of ASD boy, who researching using chelating agents - says that when given them autistic kids seem to excrete much more mercury than NTs. Not read the studies, or looked at rates of autism around Minomata? Would seem a good place to start if interested in this...

My overall view, at this time: there is a strong genetic predisposition; environmental factors (chronic, acute AND psychological) effect the degree to which that disposistion manifests. Agree totally with Prufrock - 'bit Aspie' +'bit Aspie' = strong chance of spectrum kids. Our university reunions are a bit like an Autism conference!!!

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I am the parent of a classically autistic boy, and I'm on the spectrum myself. The science of autism is my main area of interest, but I have a general interest in science and data analysis. My formal training is in Computer Science.

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